When transporting chip-type electronic components such as ICs, carrier tapes are generally used. In other words, the aforementioned chip-type electronic components are inserted into dimples for housing electronic components formed at standard intervals on the carrier tape, the top surface of the carrier tape is heat sealed with cover tape having an easily peelable adhesive layer on a substrate to seal the electronic components, then wound into a reel for transport. While the aforementioned cover tape must be transparent enough to enable inspection of the electronic components and to enable it to be smoothly peeled from the carrier tape with ease, if the electronic components are also components that easily undergo insulation breakdown due to static electricity from ICs or the like, one or both surfaces of the cover tape may be treated with an antistatic treatment in order to prevent adherence of dust, protect the contents from static electricity, and prevent problems such as the electronic components sticking to the cover tape and flying out when the cover tape is peeled from the carrier tape.
The antistatic treatment may be performed using a method such as blending an antistatic agent into the resin forming the surface to be static-proofed, or by thinly coating the surface with an antistatic agent. Examples having an antistatic agent coated onto the surface of an adhesive layer (or heat seal layer) are disclosed in Patent Documents 1 and 2.
With these methods, antistatic agent must be coated in bulk to obtain sufficient antistatic effects, and when placed in a high-temperature high-humidity environment while heat sealed to carrier tape, they attract oxygen and moisture from the air, causing reductions in the adhesive force of the cover tape as a result of which vibrations during transport and mounting can cause the cover tape to peel, and the electronic components may spill out.
Additionally, methods of static-proofing cover tape by coating the surface of the adhesive layer (heat seal layer or sealant layer etc.) with a coating containing conductive microparticles have been proposed (e.g., Patent Documents 3, 4 and 5). However, with these methods, it is not easy to evenly disperse microparticles in the resin components forming the coating material, and this not only complicates the manufacturing process and reduces productivity, but also causes dispersion defects. Additionally, in the latter method wherein an antistatic agent is kneaded in, sufficient surface resistance cannot be obtained, and mixing metal microparticles may cause the transparency to drop, making it difficult to achieve enough transparency to be able to observe printing or the shapes of contents through the cover tape.
On the other hand, in recent years, a coating-type antistatic agent using an ionic liquid has been proposed for static-proofing films or sheets in general (e.g., Patent Document 6). However, there do not seem to be any documents that disclose coating the surface of the heat seal layer of cover tape, or its effect on peel strength.    Patent Document 1: JP H7-172463 A    Patent Document 2: JP 2005-225548 A    Patent Document 3: JP H11-115088 A    Patent Document 4: JP H7-251860 A    Patent Document 5: JP 2003-266016 A    Patent Document 6: JP 2010-121093 A